Gas turbine engine block

ABSTRACT

A regenerative gas turbine engine includes an engine block or frame having two end faces and four side faces with a bulkhead dividing the interior of the block into a chamber for high pressure air discharged from the compressor and a chamber for low pressure gas discharged from the turbine. The turbine is mounted centrally in the bulkhead and regenerator disks are mounted on two opposite faces of the block. The bulkhead defines a support for cross-arm seals of the regenerator and is of a double-walled construction providing a cooling air passage through the bulkhead tapering from one end toward the center and then diverging towards the other end of the passage.

United States Patent Bell, III

GAS TURBINE ENGINE BLOCK Inventor: Albert H. Bell, III, Birmingham,

Mich.

Assignee: General Motors Detroit, Mich.

Filed: Oct. 9, 1970 Appl. No.: 79,730

[73] Corporation,

References Cited UNITED STATES PATENTS 8/1965 Chute ..l65/9 [is]3,680,983 1 Aug. 1, 1972 3,490,746 1/1970 Bell ..4l5/l 77 PrimaryExaminer-Robert M. Walker Attorney-Paul Fitzpatrick and Jean L.Carpenter 5 ABSTRACT A regenerative gas turbine engine includes anengine block or frame having two end faces and four side faces with abulkhead dividing the interior of the block into a chamber for highpressure air discharged from the compressor and a chamber for lowpressure gas discharged from the turbine. The turbine is mountedcentrally in the bulkhead and regenerator disks are mounted on twoopposite faces of the block. The bulkhead defines a support forcross-arm seals of the regenerator and is of a double-walledconstruction providing a cooling air passage through the bulkheadtapering from one end toward the center and then diverging towards theother end of the passage.

2 Claims, 7 Drawing Figures GAS TURBINE ENGINE BLOCK My inventionrelates to gas turbine engines, and parregenerative gas turbine engineof a type specially suited to use in heavy vehicles.

While there may be advantages to saving weight in power plants for anysort of vehicle, it seems to be the case that the aircraft heritage ofpresent gas turbines has overinfluenced designers of such engines in thedirection of light weight. The result is that engines are designedprimarily as minimum weight sheet metal structures, with attendantdisadvantages. It has occurred to me that a gas turbine engine which isintended to replace a diesel engine in a heavy truck, tractor or otherrelatively heavy vehicle suffers very little penalty from substantialweight, and that trade-offs to reduce weight are generally inadvisablein an engine intended for such purposes.

Pursuing this thought has led to the conclusion that the frame, housing,or engine block of a regenerative gas turbine for heavy vehiclepropulsion may well be a substantial or massive casting or weldmentrather than a relatively flimsy fabricated sheet metal structure. Theweight of a rigid casting or a weldment from relatively heavy plate isno substantial disadvantage in such an environment. The greater rigidityand ease of fabrication and the opportunity to use materials readilyobtainable and castable or weldable to provide a strong rigid supportingstructure for the engine and its accompanying reduction gear andaccessories can be exploited beneficially by following the principles ofmy invention.

My invention involves another aspect; that is, of providing improvedcooling of the parts of the engine block immediately adjacent theturbine and regenerator, which are quite hot, and reinforcement of theengine bulkhead structure to provide a high degree of strength andrigidity, by use of a hollow ventilated double-walled bulkhead andcross-arm seal support.

The principal objects of my invention are to provide an improved overallstructure or framework, which I call an engine block, for an engine ofthe type referred to. A further object of the invention is to provide anexceptionally sturdy and economically feasible structure of a gasturbine engine. A further object is to provide improved arrangements forcooling and strengthening the bulkhead of a regenerative gas turbineengine. A still further object is to promote an unforced cooling airflow through the bulkhead.

The nature of my invention and its advantages will be apparent to thoseskilled in the art from the succeeding detailed description andaccompanying drawings of the preferred embodiment of the invention.

In the drawings,

FIG. 1 is a sectional view of the major part of a regenerative gasturbine engine, taken on a plane containing the axis of rotation of theturbo-machinery, with parts broken away and in section.

FIG. 2 is a horizontal sectional view of the engine block taken on theplane indicated by the line 2-2 in FIG. 1.

FIG. 3 is a side elevation view of a portion of the engine block, withparts cut away.

FIG. 4 is a vertical sectional view of the engine block, with parts cutaway.

FIG. 5 is a horizontal sectional view taken on the plane indicated bythe line 5-5 in FIG. 3.

FIG. 6 is a horizontal sectional view taken on the plane indicated bythe line 6-6 in FIG. 3.

FIG. 7 is a partial horizontal sectional view taken on the planeindicated by the line 7--7 in FIG. 3.

My present invention is illustrated in FIG. 1 as embodied in aregenerative gas-coupled gas turbine engine similar to that described inmy U.S. Pat. No. 3,490,746 granted Jan. 20, 1970. That patent isdirected particularly to the rotating structure of the engine withprovisions for improving cooling, sealing, and lubrication of turbineassembly. It may be referred to for further information about theengine, but sufficient of its organization will be described herein foran understand ing of the invention which is the subject of thisapplication.

Referring to FIG. 1, the engine includes a single stage radialcompressor 2 having a case 3 and a rotor 4. The compressor dischargesinto an annular vaned diffuser 6 which in turn discharges into agenerally annular plenum chamber 7 defined by the forward portion of agenerally rectangular engine block or case 8, on which the case 3 andforward wall of the diffuser are mounted. The compressed air flows fromthe plenum chamber 7 through outlets in the side of the block andreturns to the interior of the block through the forward portion of anaxial-flow regenerator matrix mounted on each lateral face of the blockfor rotation about a horizontal axis. The regenerator matrix is notillustrated, but structure of a suitable axial-flow regenerator matrixand seal arrangement is illustrated in Bracken and Zeek U.S. Pat. No.3,368,611, issued Feb. 13, 1968.

The compressed air, heated by passing through the regenerator matrix,enters the interior of the block 8 through an opening 10 in the sideface of the block and flows into a combustion liner 11 within which fuelis burned and from which the combustion products flow through a scroll12 into a first stage turbine nozzle 14. This turbine nozzle is mountedon an approximately cylindrical turbine case 15 which defines the outerwall of a motive fluid conduit 16. The inner wall of the motive fluidconduit is defined by a bearing housing 18 and an inner shroud 19 of asecond stage turbine nozzle, which nozzle includes vanes 20 extendingbetween the inner shroud and the case 15. A flange 22 extending aroundthe turbine case 15 is bolted to a bulkhead 23 which is an integral partof the engine block 8, extending across the interior of the block anddividing it into a high pressure chamber into which the compressed airflows from the regenerator and a low pressure chamber through which theturbine exhaust is conducted to the regenerator. The lateral edges ofthe bulkhead define cross-arm seal supports 24 (see also FIGS. 2 and 3).

The combustion liner 1 l is mounted under a removable combustion chambercover 26 which mounts the fuel nozzle 27 to inject fuel into the linerand an igniter 28. The combustion products developed in the liner flowthrough the scroll l2, nozzle 14, the blades of a high pressure turbinewheel 30, the motive fluid conduit 16, nozzle vanes 20, and the bladesof a low pressure turbine wheel 31. The exhaust from the low pressureturbine flows through a diffusing passage 32 into the space rearward ofbulkhead 23 from which it flows through arcuate openings 34 in each sideface of the engine block 8, outwardly through the regenerator matrix ateach face, and into exhaust structure (not illustrated).

The high pressure turbine 30 is mounted on a shaft 35 by which thecompressor rotor 4 is driven, the compressor and turbine with thecombustion apparatus constitutingv a gas generator.

The high pressure and low pressure turbines constitute a turbineassembly generally contained within or fixed to the turbine case 15. Thelow pressure or power output turbine 31 is mounted on a shaft 38supported within the bearing housing 18 and within a reduction gear case39 within which is mounted reduction gearing 40 and accessory drivegears (not identified) which provide the drive for engine drivenaccessories and which include gearing 42 which is coupled to theregenerator matrices for rotation of these about their common axis ofrotation.

Having described the general organization of the engine, we now proceedto consideration of the engine block 8 in more detail. As has beenstated, the engine block is a generally rectangular structure having topand bottom faces, right and left side faces, and front and rear ends,the front end mounting the compressor and providing a plenum chamberinto which the compressor discharges, the side faces mounting theregenerator matrices, and the enclosing covers for the matrices andexhaust outlet (not illustrated), and the rear end of the. blockmounting the reduction gear and accessory drive arrangement. An oil sump(not illustrated) may be provided on the bottom face of the block.Referring now generally to the drawings, the cross-arm seal support 24which extends from top to bottom at each side of the block is shown inmost of the figures. It may be noted that this is slightly concave orbowed from end to end as viewed from the outside of the block, asindicated most clearly at the right side of FIG. 4. The effect of thisis to conform more closely to the matrix after it expands differentiallyand adopts a somewhat dish-shaped configuration in operation.

The side faces of the block 8 define circular faces 43 which provide abacking for circumferential seals between the engine block and therotating matrix and also define bolt holes 44 by which the regeneratorcover and exhaust connection is mounted. The cross arm seal support 24defines a threaded opening 46 at the center of rotation of the matrixinto which is inserted a bolt which provides an axle on which the matrixis rotated.

The bulkhead 23 is a double-walled structure defined by a forward wall47 and a rear wall 48. The two walls are joined at the center of theblock by a turbine mounting ring 50 which is provided with threaded studI FIGS. 5, 6, and 7. The rear wall 48 diverges from the forward walltoward the top and bottom of the block and is of a rearwardly domedoutline as shown clearly in FIGS. 5 and 7, approaching close to theforward wall 47 at the cross-arm seal support 24 and being quitesubstantially spaced from it on the center plane of the en gine at thetop and bottom of the block.

As will be apparent, this structure provides a rather large unobstructedentry for cooling air at into the lower end of the air conduit definedby the hollow bulkhead. This conduit, which is indicated as 56 in FIG.7, divides into two passages identified as 58 and 59, which pass aroundthe turbine mounting ring 50 and turbine case 15, the two passages againuniting into an upper diverging outlet conduit 60. The naturalcirculation through the hollow bulkhead is thus caused to flow mostrapidly adjacent the turbine which liberates a very considerable amountof heat and there is in essence a venturi effect which causesacceleration and deceleration of the air flowing upward through thepassage 55 to 60 so as to flow most rapidly around the turbine mountingring 50. The circulation of air through the bulkhead also carries awayheat by conduction through the metal and convection by the air from thecross-arm seal supports 24 which are in close proximity to the matrixwhich is heated by the exhaust from the turbine.

The lugs 62 illustrated in FIG. 3 are provided to mount a heavycontainment ring around the hollow turbine rotor 31 outside the turbinecase.

It is preferred that the bulkhead be cooled by air flow induced by thechimney effect of the generally vertical heated conduit. However, aircirculation may be forced by a fan or otherwise if desired, and theconvergentdivergent cooling passage configuration is advantageous inthis case also.

It may be noted that in practice the bulkhead will have a coating (notillustrated) of thermal-insulating material over it to minimize transferof heat by conduction from the hot turbine exhaust or by radiation fromthe combustion chamber and turbine case. This is common practice.

It should be apparent to those skilled in the art that the structure ofthe block provides an exceptionally rigid and suitable mount for thevarious components of the engine and accessory devices mounted on it, aswell as the power takeofl' through the reduction gear to drive thevehicle or other load. It should also be apparent that the structure isone readily adapted to casting and further clear that the hollowstructure of the bulkhead with the converging and diverging air passageis well suited to provide a desired degree of cooling of the bulkheadwithout forced circulation of air.

The detailed description of the preferred embodiment of the inventionfor the purpose of explaining the principles thereof is not to beconsidered as limiting or restricting the invention, as manymodifications may be made by the exercise of skill in the art withoutdeparting from the spirit of the invention.

I claim:

l. A gas turbine engine comprising, in combination, an engine block ofgenerally rectangular outline, having two end faces and four side faces,defining an interior space, and including a bulkhead dividing the spaceinto a high pressure chamber and a low pressure chamber; a turbineassembly mounted on the bulkhead;

faces, the walls defining between them an air circulation conduit openat the top and bottom faces of the block and. diverging in area from thering in each direction, the said lateral edges of the bulkheadconnecting the said bulkhead walls so that the cross-arm seal supportsare cooled by circulation through the conduit.

2. An engine as recited in claim 1 in which the said engine block is anintegral casting.

1. A gas turbine engine comprising, in combination, an engine block ofgenerally rectangular outline, having two end faces and four side faces,defining an interior space, and including a bulkhead dividing the spaceinto a high pressure chamber and a low pressure chamber; a turbineassembly mounted on the bulkhead; a compressor driven by the turbineassembly mounted on one end face of the engine block; an output geardriven by the turbine assembly mounted on the other end face of theengine block; the engine block including means for mounting rotaryregenerators on opposite side faces of the block and the bulkhead havinglateral edges defining cross-arm seal supports for the regenerators; thebulkhead including a central ring for mounting the turbine assembly andtwo mutually spaced walls extending from the ring to the four sidefaces, the walls defining between them an air circulation conduit openat the top and bottom faces of the block and diverging in area from thering in each direction, the said lateral edges of the bulkheadconnecting the said bulkhead walls so that the cross-arm seal supportsare cooled by circulation through the conduit.
 2. An engine as recitedin claim 1 in which the said engine block is an integral casting.